code: def test_fit_mean(self):
      gpa = prince.GPA(init="mean")
      self.assertIsInstance(gpa.fit(self.shapes), prince.GPA)
  
file_path: prince/tests/test_gpa.py
imports: from __future__ import annotations
  import unittest
  import numpy
  import pandas
  import prince
label_desc: Use image node_id 4 for calling the TestGPA obj's underlying member method code with example usage: obj.test_fit_mean() without return types